Jet pump



May 26, 1959 E. P. NEUMANN ETAL 2, 9

JET PUMP Filed May 3, 1954 2 Sheets-Sheet 1 INVENTORS ERNEST P. NEUMANNBY FERDINAND LUSTWERK wwwvw ATTORNEYS y 1959 A E. P. NEUMANN ETAL2,888,191

JET PUMP Filed May 3, 1954 2 SheetsSheet 2 5a 'se' 44 Fig. 2

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INVENTORS H 3 ERNEST F? NEUMANN J- BY FERDINAND LUSTWERK M, M, rmv WATTORNEYS United States Patent JET PUMP Ernest P. Neumann and FerdinandLustwerk, Lincoln, Mass., assignors, by mesne assignments, to RheemManufacturing Company, a corporation of California Application May 3,1954, Serial No. 427,048

2 Claims. (Cl. 230111) This invention relates to jet pumps and inparticular to means for transferring through an ejector the standingshock waves created by the initial flow of a motive fluid into theejector body.

Of all the difliculties encountered in the operation of jet pumps, oneof the most troublesome is the impact of the motive fluid in the inletmouth of the ejector. The shock waves created by the initial impact ofthe motive fluid cause an appreciable drop in efliciency, delay in thenormal functioning of the pump and damage to the pumping apparatus.Moreover, eddy currents are created in the mouth of theejector by theimpact, which gives rise to a great deal of turbulence and prohibitsmooth performance of the pump for a considerable time after the initialstanding shock wave has passed through the ejector throat.

One important object of this invention, therefore, is to decrease theresistance to the initial surge of motive fluid in the mouth of anejector.

Another important object of this invention is to establish normallyefiicient flow conditions in the ejector a predetermined interval oftime after the pump has been started.

Still another object of this invention is to reduce the turbulence in-theejector and thereby increase the life of the pumping apparatus.

In the accomplishment of these and other objects I provide as oneimportant feature of this invention means responsive to the pressure atthe inlet of the ejector for effectively transmitting the shock throughthe throat of the ejector.

Another feature of this invention is the provision of a pressure reliefvalve in fluid communication with the mouth of the ejector to reducethe'pressure therein created by the initial surge of motive fluid.

Another feature of.the invention particularly adapted to perform theabove objects is the provision of an ejector coaxially disposed withrespect to the injector nozzle, the two being relatively movable.

As another feature of this invention I provide a movable sleevesurrounding the injector, which may be moved into the ejector mouth, andwhich restricts the size of the diverging cone of motive fluid issuingfrom the injector nozzle.

These and other objects and features of the invention will be morereadily understood and appreciated from the following detaileddescription of preferred embodiments thereof selected for purposes ofillustration and shown in the accompanying drawing, in which:

Fig. 1 is a viewin section of a jet pump constructed in accordance withthis invention,

Fig. 2 is a view in section of another jet pump constructed inaccordance with this invention, and

Fig. 3 is a view in section of still another jet pump constructed inaccordance with this invention.

Proceeding now to a detailed description of the embodiment of thisinvention shown in Fig. 1, the jet pump illustrated is organized aboutan injector nozzle and a tube 20 respectively mounted within a hood 12and casing 18. The tube 20 is longitudinally spaced from and coaxialwith the nozzle 10 and contains a movable inner sleeve 22 which servesas an ejector body. The

ejector body 22 is defined by a mixing chamber or mouth 24 convergingaway from the injector nozzle 10 and smoothly merging into a restrictedorifice or throat 26 in the ejector midsection leading to a deliverytube 28 having a gradually increasing inner diameter beyond the throat.

The injector nozzle 10 is of venturi configuration similar to theejector but of a much smaller size. The hood 12 defined as containingthe nozzle 10 has a relatively large suction tube 14 leading to anannular ehamber formed about the nozzle by the hood. The annular chamberfreely communicates with the mixing chamber 24 permitting fluidentrained into the annular chamber to pass into the mouth of the ejectorbody and mix with the motive fluid.

The structure thus far described will be recognized as conventional jetpump apparatus and is, without the additional structure'later to bedescribed, subject to the failings set forth in the introductoryparagraphs of this specification. Upon the commencement of pumpoperation themotive fluid emerging from the nozzle strikes a relativelydead column of air in the ejector; hence the standing shock wave hasdifliculty passing through the converging mouth and restricted orifice.Continued emission of the motive fluid from the nozzle will fill themouth of the ejector and destroy the low pressure area in the annularcharnber necessary for the entrainment of the fluid through the suctionconduit 14. Generally, after some appreciable delay, the shock wavewillpass through the throat of the ejector body and normal operation of thepump will then occur. However, on some occasions time Will not cure theimpaired operation and the motive fluid will back up in the nozzleoverloading the pump (not shown) moving the fluid therethrough which maydamage it and prevent further operation.

Proceeding now to a description of the apparatus comprising the heart ofthis inventive concept, it has been found that by moving the ejectorbody an appreciable distance toward the nozzle (to the positionillustrated in dotted lines in Fig. 1), the standing shock Waveaccompanying the initial emission from the nozzle will, withoutappreciable difiiculty, pass through the mixing chamber and throat ofthe ejector. Consequently, entrainment of fluid from the section tube 14commences almost immediately following the initial flow of motive fluidfrom the nozzle. No backing up of the fluid occurs and turbulence in theejector is greatly reduced. When the pump is observed to be functioningproperly, the ejector body may be moved away from the nozzle 10 to itsnormal operating position illustrated in full lines in the drawing. a

To move the ejector in the manner described a geared reversible motor 36is positioned to cooperate with a rack 30 longitudinally disposed on theejector body 22. The motor 36 is illustrated as mounted on a base 16which also serves as a mounting block for the casing 18. A pinion 34rotatably mounted on the shaft of the motor 36 engages a gear 32 whichin turn registers with the teeth of the rack. To permit the mechanicalconnection of the rack 30 and the gear 32, the tube 20 is provided witha longitudinal slot 38 of a length substantially greater than the rack.The slot 38 permits translational motion of the ejector body 22 and therack 30 between fixed limits defined by the slot. When motor 36 rotatesin a clockwise direction as viewed in the drawing, pinion 34 will rotatein the same direction, turning gear 32 counterclockwise. The rack 30will be moved to the left carrying with it the ejector 22 and will causethe mixing chamher 24 to telescopically fit over the nozzle as shown indotted lines. Initial operation of the motor may be timed with the firstemission of motive fluid from the nozzle, while after a predeterminedinterval of time the rotation of the motor may be automatically reversereturning the ejector body to the position shown in full lines in thedrawing. Although no automatic means has been illustrated to performthis function, it will be ob vious to a man skilled in the art thatnumerous means may be provided to control the motor operation. Forexample, a pressure responsive switch may be included in the powersupply line of the motor 36, which is actuated to closed position bypressure in the mixing chamber, while a timing mechanism mayautomatically reverse the motor after a predetermined interval.Alternatively the motor may be replaced by a spring and holding solenoidactuated in response to an increase in pressure in the mixing chamber orto the initial emission of fluid from the injector nozzle. Irrespectiveof the means employed to move the ejector body, a reduction in theresistance opposing the passage of the standing shock wave through themixing chamber and throat will result.

Proceeding now to a description of another embodiment of this invention,Fig. 2 illustrates a fully automatic means for reducing the resistanceto the passage of a standing shock wave through the ejector. Both theinjector nozzle and the ejector are stationary in the jet pumpillustrated. A relief valve is provided to carry out the functionperformed by the movable ejector in the previously described embodiment.

In detail, a venturi type injector nozzle 44) is mounted in a hood 42and forms therewith an annular chamber. Leading into the annular chamberis a suction conduit 44 provided as an inlet passage for the secondaryfluid to be entrained by the motive fluid discharge by the nozzle. Thehood 42 merges smoothly into a mixing chamber 46 disposed coaxially withand longitudinally displaced from the outlet of the nozzle 4%). Themixing chamber 46 converges away from the hood and terminates in arelatively narrow throat or orifice 48 of constant diameter throughoutits length. integrally formed with the hood, mixing chamber and throatis a delivery tube 50 which completes the ejector body. The diameter ofthe delivery tube 50 gradually increases away from the throat 48rendering a venturi configuration to the ejector.

The structure now to be described comprises the pressure relief meansemployed to reduce the resistance in the ejector to the passage of thestanding shock wave. A conduit 52 connected to the rear of the mixingchamber 46 adjacent the throat .8 is serially connected at its other endto a conduit 66 by a cylindrical casing 54. A piston 56 within thecylinder 54 is urged by a spring 53 to a position interrupting freecommunication between the two conduits. The conduit 52 serves as arelief tube for the ejector by carrying ofl a portion of the fluidinitially introduced into the mixing chamber by nozzle 49 and furtheracts as a pressure relief conduit for the mixing chamber. Theinstantaneous pressure surge adjacent the entrance of the throataccompanying the starting of pump operation will be transmitted by theconduit 52 into the cylinder 54, and the piston 56 will be moved to theleft against the bias of to sprin 58. The pressure surge in the mouth ofthe injector will then be dissipated from the mouth through conduit 52and out into the conduit 60. The conduit 64) which communicates with theinlet side of the mixing chamber 46 will also permit the motive fluidwhich was carried into the conduit 52 to recirculate in the system.

A third conduit 62 is connected at one end to the cylinder 54 on theside of the piston 56 opposite to that of the conduit 54 while its otherend is connected to the the mixing chamber. Any fluid that passes aroundthe piston will be directed by the conduit 62 into the mixing chamber.

In operation, the relief mechanism functions in the following manner.The initial flow from the injector nozzle 46 will cause a build up inpressure in the rear of the mixing chamber 46. This pressure build upwill, by virtue of the communicating conduit 52, move the piston 5-6 tothe left and the pressure will subsequently be released from the mixingchamber by conduit 60. The reduction in pressure adjacent the throat 43will permit the standing shock wave to pass through the ejector body anda low pressure area will then be created in the annular chamber withinthe hood 42. Entrainment of the secondary fluid will then be instituted.Simultaneously with the beginning of the pumping of the secondary fluidfrom tube 44, the pressure in the rear of the mixing chamber will beappreciably reduced, and the spring 53 will return the piston 56 tothe'right terminating communication between conduits 52 and 60. Anyfluid that has passed into the cylinder 54 and around the piston will bereturned to the mixing chamber by the conduit 62. The jet pump will thenfunction in a normal manner and any of the difficulties encountered inconventional jet pumps as recited above will have been avoided.

The embodiment of this invention illustrated in Fig. 3 employs many ofthe principles used in each of the previously described embodiments. Asis evident from a cursory inspection of the drawing, the nozzle is effectively placed in a position at the rear of the mixing chamberimmediately adjacent the throat of the ejector.

In detail, the pump apparatus is organized about an elongated conduithaving a venturi type injector comprising mixing chamber or mouth 72, athroat 74 and a delivery tube 76 integrally formed at one end. A cap orcover 71 telescopically receives the other end of the conduit 7%}closing that end. Projecting through the cap into the conduit coaxiallytherewith is a second conduit 84 which terminates adjacent the mouth ofthe mixing chamber 72. Integrally formed within the terminal portion ofthe conduit 84 is an injector nozzle for discharging motive fluid intothe mixing chamber. Radially connected to the conduit 70 adjacent thenozzle 30 is a suction line 78 which directs the fluid to be pumped intothe mixing chamber.

Thus far the description of the invention illustrated in Fig. 3 has beenlimited to rather conventional structure. The apparatus for transferringthe standing shock wave through the ejector throat will now bedescribed. A sleeve 86 is slidably mounted on the conduit 34 and is of alength approximately equal to the portion of the conduit 84 within theconduit 70.- A piston 88 is fixed on the forward end of the sleeve 86adjacent the cover 71 and is in sliding engagement with the inner wallsof the conduit 70. A pair of springs 90 fixed at-their ends to the cover71 and the piston 88 urge the sleeve to a retracted position illustratedin full lines wherein the terminal portion of the sleeve does notproject beyond the end of the nozzle 80. By means later to be describedthe sleeve 86 may be moved to its extended position (shown in brokenlines in Fig. 3) against the bias of the springs 90. In the extendedposition it effectively lengthens the nozzle 80 wherein it extends to aposition at the rear of the mixing chamber 72 juxtaposed with the throat74.

The apparatus now to be described is employed as actuating means for thesleeve. A high pressure conduit connected at one end to the conduit84.is radially connected at its other end to a hollow cylinder 94 which hasa piston valve 96 movable axially therein. A conduit Th6 radiallyconnected at one end to the cylinder 94- opposite to the connection ofhigh pressure conduit 110, communicates at its other end with theconduit '70 immediately to the left of the piston 88. A biasing spring98 within the cylinder 94 urges the piston valve 96 to a positioninterrupting the flow of fluid from the high pressure conduit 110 to theconduit 106. An annular recess 112 on the surface of the piston isadapted to permit communication of conduit 110 with conduit 106 when thepiston is moved to the left against the bias of the spring 98. A reliefconduit 100 connected to the cylinder and to the conduit 70 adjacent theend of the nozzle 80 communicates with the conduit 106 by means of aport 112 and a second annular recess 104 when the piston 96 assumes itsbiased position under the influence of the spring 98. A fourth conduit92 joined at one end to the mixing chamber 72 adjacent the throat 74 isconnected at its other end to the cylinder 94.

It will be seen that the initial emission of the motive fluid from thenozzle 80 will create a high pressure area at the rear of the mixingchamber. The pressure surge Will be transmitted to the cylinder byconduit 92 and piston 96 will be moved to the left placing the recess11?. in a position to connect the conduits 110 and 106. A portion of thehigh pressure motive fluid in the conduit 84 will pass through theconduit 110, the annular recess 112, and the conduit 106 into theconduit 70 to the left of the piston 88. The pressure build up at thatlocation will move to the right the piston 88 and with it the sleeve 86.The sleeve will assume its extended position as suggested by thedot-and-dash lines in the drawing.

Extended sleeve 86 will restrict the size of the diverging cone ofmotive fluid issuing from the nozzle 80 and the fluid will be guidedthrough the throat 74. The passage of the motive fluid through theorifice 74 will cause a pressure drop in the mixing chamber and thestanding shock wave will pass through the ejector throat. Moreover, thesecondary fluid will be drawn into the mixing chamber 72 from thesuction tube 78. The reduced pressure in the chamber will further resultin a reduction of the pressure against the piston 96, and the spring 98will return it to its biased position discontinuing registration ofrecess 112 with conduits 110 and 106. The high pressure conduit 110 nolonger being in fluid communication with the conduit 106, the springs 90will return the sleeve to the retracted positionjshown in full lines.The fluid to the left of the piston 88 will be forced out of the conduit70 through the conduit 106, and the port 108, the slot 104 and theconduit 100 will carry the fluid into the conduit 70. A conduit 102merging into conduit 100 is adapted to drain away any accumulated fluidin the cylinder.

It is seen that each of the embodiments illustrated efiectively reducesthe pressure build up at the mouth of the ejector thereby reducing theresistance to the standing shock wave. As a result the disadvantages ofjet pumps discussed in the introductory paragraphs of the specificationare either appreciably reduced or entirely eliminated.

Obviously numerous minor variations of the illustrated embodiments ofthis invention will occur to one skilled in the art to which thisinvention pertains. Therefore, it is our intention that this inventionbe limited only by the appended claims and not by the specificallydescribed embodiments.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A jet pump comprising in combination a pump body which includes achamber, a converging mouth and a restricted throat, a suction tubeconnected to supply fluid to the chamber, an injector nozzle located inthe chamber rearwardly of and coaxially with the throat, a pressure tubeconnected to supply motive fluid through said nozzle and projectivelytoward said throat, conduit means connected to said chamber adjacent thereduced end of said mouth adjacent said throat and to a rearward portionof said chamber adjacent said injector nozzle, a normally closed biasedvalve operatively positioned in said conduit means, said valve beingoperative to open in response to a predetermined abnormal pressure insaid mouth generated by the operation of said nozzle to direct fluid tosaid rearward portion of said chamber and thereby reduce said pressure,and means normally maintaining said valve in closed position.

2. A jet pump comprising in combination a pump body which includes achamber having a converging mouth and a restricted throat, a sleeveaxially slidable in the pump body, a suction tube connected to supplyfluid to the chamber, an injector nozzle whose external diameter issmaller than the maximum internal diameter of said mouth and positionedaxially within said sleeve, said nozzle having a flaring orifice whosemaximum diameter is smaller than the diameter of said throat, saidnozzle being located in the chamber coaxially with and rearwardly of thethroat, a pressure tube connected to supply motive fluid through saidnozzle and projectively toward said throat, means normally urging saidsleeve rearwardly whereby said nozzle orifice extends forwardly of thesleeve end, conduit means operatively connected to said converging mouthportion of said chamber, and plunger means operatively engaged with saidsleeve and in operative communication with said conduit means for urgingsaid sleeve forwardly towards said throat upon abnormal pressureconditions existing in said converging mouth portion and said conduitmeans.

References Cited in the file of this patent UNITED STATES PATENTS Re.6,006 Rue Aug. 11, 1874 74,346 Gresham Feb. 11, 1868 1,415,406 ScanesMay 9, 1922 1,421,840 Schmidt July 4, 1922 1,421,841 Schmidt July 4,1922

